JP2007503614A - System for driving an inertia display image display device - Google Patents

Abstract

  A system for driving an inertial-prone image display device, in particular a system for driving a liquid crystal display, in which a correction value corresponding to a change in the video signal from frame to frame is used to compensate for the inertia effect In a system in which a corrected video signal is to be added to the signal and passed to the image display device, a block associated with the model of the image display device is used to generate the correction value. And the model has a state variable as an output variable, the video signal as a first input variable, and the state variable from a previous frame as a second input variable. Further, a block relating to a function is provided for deriving the correction value, and the function includes the input video signal and the state variable of the preceding frame as input variables, and the output variable includes the input variables. Has a corrected video signal.

Description

  The present invention relates to a system for driving an inertia-prone picture-reproducing device, in particular a system for driving a liquid crystal display, in which a video signal from frame to frame is represented. A correction value corresponding to the change is added to the input video signal in order to compensate for the initial effect, and the corrected video signal is passed to the image display device.

  Liquid crystal displays (LCDs) are known for poor transient response. A sudden change in the input video signal between two consecutive frames does not cause a corresponding sudden change in the brightness emitted by the LCD. Instead, the liquid crystal display shows significant inertia and the emitted luminance is gradually approaching the default value. The transition may continue over a plurality of frame periods (refresh cycles). This behavior in particular results in motion disturbances in a moving frame sequence, in particular in which the edges are displayed in a blurred form. The disturbance of motion depends on the current video signal amplitude at each time point and the preceding video signal. In addition, the brightness response of a liquid crystal display depends on the particular technology being used.

  Since the edges of moving objects in the frame sequence are ambiguous, this effect is also referred to below as motion blur. For example, in the method disclosed by US6304254 (patent specification), each preceding frame is accumulated. The values of the individual pixels of the current frame and the previous frame are stored in a table from which correction values are read, which leads to an overdrive of sudden changes in the video signal. As a result, motion blur can be improved to a first order approximation. However, the known methods have various disadvantages. For example, overdrive exceeding the limit of the amplitude range of a liquid crystal display amplifier is not allowed. However, if overdrive is not sufficient as a result, subsequent corrections can no longer be made after a sudden change as described above due to the lack of just one frame.

  US2002 / 0175907 (open specification) discloses a system comprising a liquid crystal display, in which the predicted value for the value of the capacitance of the component of the liquid crystal display generates a correction value. Used for. The liquid crystal used in this system does not adapt itself to a specific situation in a very short time, but slowly changes the capacitance of the individual components, so that the applied voltage also changes. This is the fact. In this known system, the capacitance value is stored as a function of the applied voltage and as a result indirectly serves as an overdrive measure to be applied.

  The system according to the invention comprises a block relating to a model of an image display device, said model having a state variable as an output variable and a video signal as a first input variable for generating a correction value. And a state variable from the previous frame is provided as a second input variable, and a function block is provided for deriving a correction value, and the function is input video as an input variable. A signal and a state variable of the previous frame, and a corrected video signal as an output variable. With the system according to the invention, motion blur is improved. The function is preferably stored in a table.

  The state variable is in this case a numerical representation of the variable derived from the temporal change in brightness generated by a sudden signal change. The variable may be, for example, luminance at the end of the frame period or luminance averaged over the frame period.

  Compared to the known method described above, the system according to the invention has the following advantages. That is, the overdrive is improved, so that if the correction cannot be performed in a single step (from frame to frame), the overdrive will not cause a system error. Instead of the known method described above, in the case of the present invention, only a limited dynamic range is required and optimal correction can be performed over two or more frames. In addition, even if a single-stage correction can be performed in principle, the correction can be easily applied over a plurality of frames.

  This flexibility is advantageous for a variety of reasons. Using a liquid crystal display time model to determine overdrive typically limits accuracy. If correction from one frame to the next is attempted, this can easily lead to overcompensation of moving edges. However, the system according to the present invention can reliably make adjustments that cover the correction over a plurality of frames, so that any over-compensation can be eliminated.

  It should be noted that the initial behavior of the liquid crystal display is extremely asymmetric, which means that the behavior at the rising edge is substantially different from the falling edge of the video signal. This can result in only one of the two opposing edges of the moving object being correctable in one step, i.e. from one frame to the next, The situation is that the opposite edge requires correction over a plurality of frames. The edge method results in an asymmetrical disturbance and the required number of frames is available for the correction of the method according to the invention.

  Compared to the known systems described above, the system according to the invention has the advantage that most of the luminance response to a particular video signal is fully considered. The luminance response can be determined metrologically in advance depending on the type of liquid crystal display, whether it is a product or a sample.

  In an advantageous embodiment of the invention, the corrected video signal is the first input variable of the model. However, since a correction value is known in each case, other embodiments can be proposed in which the input video signal is the first input variable and the model derives the correction value. . This embodiment can be simplified in that the model and the table for deriving the correction value are combined in a common table.

  It is possible to propose a further embodiment in which the input video signal and the correction value are added to the common table.

  In order to keep the storage device for the table or the model as small as possible and to keep it cheap as a result, the input variable and the insert node of the output variable are stored in the model, and It is further possible to propose a system according to the invention in which means for insertion between the insertion nodes are provided.

  These and other aspects of the invention will be apparent from and will be elucidated with reference to the embodiments described hereinafter.

  Referring to the drawings, in which the exemplary embodiments are actually shown as block circuit diagrams, as well as portions thereof. However, this does not mean that the system according to the invention is limited to embodiments with individual circuits corresponding to blocks. Conversely, the system according to the invention can be implemented in a particularly advantageous manner using large scale integrated circuits. In this regard, a microcomputer with appropriate memory may be used with appropriate programming to perform the processing steps shown in the block circuit diagram.

  The known system shown in FIG. 1 has an input terminal 1 for an input video signal Vi, and the input video signal Vi is sent to an output terminal 3 via an adder 2 from which a corrected video signal is sent. Vo is sent to a liquid crystal display (not shown). The video signal takes the form of a digital signal, and each value is assigned to each pixel. These values are stored in the storage device 5 for each frame or each image, and at the same time, as the input variable of the lookup table (overdrive LUT), the previous frame (read from the frame storage device 5). Sent with value A. For each pair A, B, B includes a correction value C. The correction value C obtained from the look-up table 4 is selected in such a way that the best possible compensation for motion blur is performed and passed to the adder 2. As seen in FIG. 1, in addition to the current frame, only the previous frame is considered when obtaining the correction values.

  In the system according to the invention shown in FIG. 2, the correction value B + C of the video signal Vo is sent to the model 6 of the liquid crystal display. The model reproduces the luminance response of the liquid crystal display for each input video signal and is therefore referred to as a “response model”. The output variable S is stored in the frame storage device 5. The variable S ′ read from the frame storage device 5 of the preceding frame is used as an input variable of the model 6 in addition to B + C. This results in a repetitive structure in which a plurality of previous frames are considered when deriving the correction value C. Like the variable A already described in connection with FIG. 1, S ′ is sent along with the value B to the lookup table 4.

  In the second exemplary embodiment shown in FIG. 3, an extended model 7 is used that includes the values B and S 'as input variables. Compared to the exemplary embodiment shown in FIG. 2, the extended model 7 takes into account the correction value C. This is because the correction value C depends only on the variables B and S ′. In other respects, the exemplary embodiment shown in FIG. 3 is identical to the exemplary embodiment shown in FIG.

  Compared to the exemplary embodiment shown in FIG. 3, in the third exemplary embodiment shown in FIG. 4, a table for generating the correction value C is combined with the model to form a common table 8. ing. Finally, in the fourth exemplary embodiment shown in FIG. 5, an adder 2 (FIG. 4) is provided in the table 9. As an example of the size of the table, there is a case where the address area is 16 bits and the word size is 16 bits per channel in each case (for example, R, G, B). 8 bits are used for the output signal and 8 bits are used to hold the variable S. The size of the frame storage device 5 is similarly 8 bits.

1 shows a block circuit diagram of a system for performing a known method. 1 shows a block circuit diagram of a first exemplary embodiment. FIG. FIG. 3 shows a block circuit diagram of a second exemplary embodiment. FIG. 6 shows a block circuit diagram of a third exemplary embodiment. FIG. 6 shows a block circuit diagram of a fourth exemplary embodiment.

Claims (7)

A system for driving an inertial-prone image display device, particularly a system for driving a liquid crystal display, in which a correction value corresponding to a change in a video signal from frame to frame is used to compensate for an inertial effect. In a system adapted to be added to a signal and wherein a corrected video signal is to be passed to the image display device,
A model of the image display device is provided to generate the correction value, the model having a state variable as an output variable, the video signal as a first input variable, and a second Having the state variables from the previous frame as input variables;
Furthermore, a function is provided for deriving the correction value, the function comprising the input video signal acting as an input variable and the state variable of the preceding frame, and the correction video as an output variable. A system comprising a signal.   The system of claim 1, wherein the function is stored in a table.   The system of claim 1 or 2, wherein the corrected video signal is the first input variable of the model.   3. The system according to claim 1, wherein the input video signal is the first input variable, and the model derives the correction value.   3. The system according to claim 1, wherein the model and the table for deriving the correction value are combined in a common table.   6. The system according to claim 5, wherein the input video signal and the correction value are further added to the common table.   7. An insertion node for the input variable and the output variable is stored in the model, and means for inserting between the insertion nodes is provided. The described system.

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